a integral embedded in Diff eq........

i am solving for a system of df eq's, but the eq's have these little tricky integrals inside them.....so it either retards operation or no solutoin can be found...They look like...

```B_12:=(10*a_2*a_3)*(u/( ((10^2+u)^(3/2)) * ((a_2^2+u)^(3/2)) * ((a_3^2+u)) )):
B_122:=(10*a_2*a_3)*(u/( ((10^2+u)^(3/2)) * ((a_2^2+u)^(5/2)) * ((a_3^2+u)) )):
B_123:=(10*a_2*a_3)*(u/( ((10^2+u)^(3/2)) * ((a_2^2+u)^(3/2)) * ((a_3^2+u)^(3/2)) )):
B_23:=(10*a_2*a_3...```

Plotting a point plot..........

`My problem looks as follows................pts1FIXED comes from dsolved solution......it plots a empty figure...and i checked that l(the data pairs looks fine)..`
`--------------------------------------`
```Energy:=array(1..450);
Time:=array(1..450);
for i from 1 to 450 do

Energy[i]:=-1*((32*G*Inertia^2*e^2)/(5*c^2))*pts1FIXED(i);
end do:
l := [[t,Energy[t]] \$t=1..450]:
plot(l,style=point,symbol=circle,color=blue);
```

I need some help...i need a solver using the Runge-Kutta method adaptive size control, to solve a sytem of 5 diff eq's, all of them are interlinked...

And

Say that dsolve numeric produces a results, called Solution, Now ex  solution(0)=1, and in general solution(t) can be evaluated, now, i want to use this, in E(t)=2*solution(t), in a plot, thus...

plot(E(t),t=0..100,....), but returns the error....

writefile syntax...

I have some numerical data, which are very accurate (500 digits) and want to copy them on a text file.

For pratical reason I would like the procedure writefile to write just 20 digits figures: which is the right syntax to use?